A multicarrier transmitter is shown having an embodiment of the invention. Sampling of modulated and amplified signals is done to obtain energy values for four or more symbols. Combining the energy values with the baseband in-phase and quadrature signals of the multiple carriers may result in a set of imbalance parameters, which are subsequently stored. Later baseband in phase and quadrature signals are predistorted or compensated by applying the stored imbalance parameters to produce new compensated baseband in-phase and compensated baseband quadrature signals, which are suitable for input to an inverse fast fourrier transform (IFFT) block.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for providing a first quadrature compensated data symbol (FQCDS), a second quadrature compensated data symbol (SQCDS), a first in-phase compensated data symbol (FICDS) and a second in-phase compensated data symbol (SICDS) to an inverse fast fourrier transform (IFFT) of a multicarrier quadrature modulator having an amplifier, wherein at least four transmitted symbols are available from the amplifier and at least four data symbols and a next data symbol are available from a mapper, comprising the steps of: a) calculating the energy of the at least four transmitted symbols; b) calculating an alpha, an epsilon and a gain based on the energy of the at least four transmitted symbols and the at least four data symbols, wherein the alpha, epsilon and gain are imbalance parameters; c) storing the alpha, epsilon and gain; d) first quadrature compensating the next data symbol of a first quadrature subcarrier based on the alpha, epsilon and gain to produce the FQCDS; e) second quadrature compensating the next data symbol of a second quadrature subcarrier based on the alpha, epsilon and gain to produce the SQCDS; f) first in-phase compensating the next data symbol of a first in-phase subcarrier based on the alpha, epsilon and gain to produce the FICDS; g) second in-phase compensating the next data symbol of a second in-phase subcarrier based on the alpha, epsilon and gain to produce the SICDS; h) repeating steps a, b and c wherein the at least four transmitted symbols include a next transmitted data symbol and the at least four data symbols include the next data symbol.
2. The method of claim 1 wherein the step of calculating the alpha, epsilon and gain further comprises the steps of: calculating a first alpha, a first epsilon and a first gain based on the energy of the at least four transmitted symbols; calculating a second alpha, a second epsilon and a second gain based on the energy of the next data symbol; calculating the alpha based on an average of the first alpha and the second alpha; calculating the epsilon based on an average of the first epsilon and the second epsilon; and calculating the gain based on an average of the first gain and the second gain.
3. The method of claim 1 wherein the step of calculating the energy of at least four transmitted symbols further comprises the steps of: a) squaring output of a transmitter to provide a squared signal; b) sampling the squared signal to provide a squared sample signal; and c) integrating the squared sample signal over a symbol duration.
4. An apparatus for providing a first quadrature compensated data symbol (FQCDS), a second quadrature compensated data symbol (SQCDS), a first in-phase compensated data symbol (FICDS) and a second in-phase compensated data symbol (SICDS) to an inverse fast fourrier transform (IFFT) of a multicarrier quadrature modulator having an amplifier, wherein at least four transmitted symbols are available from the amplifier and at least four data symbols and a next data symbol are available from a mapper comprising: a) means for calculating the energy of the at least four transmitted symbols; b) means for calculating an alpha, an epsilon and a gain based on the energy of the at least four transmitted symbols and the at least four data symbols, wherein the alpha, epsilon and gain are imbalance parameters; c) means for storing the alpha, epsilon and gain; d) means for first quadrature compensating the next data symbol of a first quadrature subcarrier based on the alpha, epsilon and gain to produce the FQCDS; e) means for second quadrature compensating the next data symbol of a second quadrature subcarrier based on the alpha, epsilon and gain to produce the SQCDS; f) means for first in-phase compensating the next data symbol of a first in-phase subcarrier based on the alpha, epsilon and gain to produce the FICDS; g) means for second in-phase compensating the next data symbol of a second in-phase subcarrier based on the alpha, epsilon and gain to produce the SICDS; h) means for repeating implementation of a, b and c wherein the at least four transmitted symbols include a next transmitted data symbol and the at least four data symbols include the next data symbol.
5. The apparatus of claim 4 wherein the means for calculating the alpha, epsilon and gain further comprises: means for calculating a first alpha, a first epsilon and a first gain based on the energy of the at least four transmitted symbols; means for calculating a second alpha, a second epsilon and a second gain based on the energy of the next data symbol; means for calculating the alpha based on an average of the first alpha and the second alpha; means for calculating the epsilon based on an average of the first epsilon and the second epsilon; and means for calculating the gain based on an average of the first gain and the second gain.
6. The apparatus of claim 4 wherein the means for calculating the energy of at least four transmitted symbols further comprises: a) means for squaring output of a transmitter to provide a squared signal; b) means for sampling the squared signal to provide a squared sample signal; and c) means for integrating the squared sample signal over a symbol duration.
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December 29, 2000
June 20, 2006
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